Method of manufacturing a meltspinning spinneret



Sept. 9, 1969 om- 05 ETAL 3,465,618

METHOD OF MANUFACTURING A MELT-SPINNING SPINNERET Filed Dec. 23. 1966@QQIZIII."

FIGJ.

INVENTORS u. K. McINT PAUL T. HOWSE,

EUE 03H JR.

7n. 'Taw r ATTORNEY United States Patent 3,465,618 METHOD OFMANUFACTURING A MELT- SPINNING SPINNERET Euell K. McIntosh and Paul T.Howse, Jr., Pensacola,

Fla., assignors to Monsanto Company, St. Louis, Mo.,

a corporation of Delaware Filed Dec. 23, 1966, Ser. No. 604,287 Int. Cl.B21k 5/20 U.S. Cl. 76107 1 Claim ABSTRACT OF THE DISCLOSURE Meltspinning spinnerets are made by forming in a spinneret a hole of twodifferent diameters. A hollow insert is press-fitted in the hole so thatthe insert extends slightly below the plane of the extrusion face of thespinneret. The insert has a counterbore communicating with a series ofsmall passageways extending to the point of extrusion where thepassageways form a pattern adapted to produce a textile filament by thecoalescence of a cluster of small streams of polymer at a point belowthe spinneret face. The resulting filaments have a multitude of lobesand axially extending voids. During employment of the spinneret, ringssurrounding the individual filaments can be used to supply a coolingfluid to solidify the filaments in a controlled manner shortly after theemergence of the streams of molten polymer from the spinneret.

BACKGROUND OF THE INVENTION It is well known to provide melt-spunfilaments with one or more continuous axially extending holes in orderfor the filaments to have increased cover when used in the constructionof fabrics and the like. A practical way of producing such filaments isto use an orificial grouping of a plurality of elongated segments in aspinneret permitting passage therethrough of molten fiberforming polymerfor each filament produced, such as disclosed in U.S. Patent 3,174,364.The segments are disposed with respect to each other within eachorificial group in such a manner that the ends of the plurality ofmolten streams of polymer extruded through the segments within theorificial group coalesce endwise shortly after issuing from theorifices. There are definite limitations as to the total amount of voidthat one can obtain in a filament produced by the coalesce of smallpolymer streams. For example, when one uses nylon-66 polymer of normalrelative viscosity of, say 30 55 and conventional filament solidifyingequipment, a void percentage of the total area occupied by the filamentusually will not exceed -15%. Accordingly, it would be desirable toincrease the amount of void that one can obtain at practical meltspinning speeds.

It has been suggested to provide lobes or branches in textile filamentsto obtain increased cover. However, multilobal filaments possessingcross-sectional symmetry exhibit sparkles of lights as can be seen fromU.S. Patents 2,939,2012,939,202. Such sparkle is referred to asprismatic luster because the filaments actually reflect and refractlight as a prism. In many end uses filaments having such sparkle are notdesirable because fabrics made therefrom may be regarded by customers asbeing garish.

It has been disclosed in U.S. 2,965,925 to provide continuous axiallyextending holes in the lobular sections of man-made filaments. However,the prismatic phenomenon causing the garish sparkle in certainmultilobar filaments still occurs. To even a greater extent it would bedesirable to increase the amount of void in man-made filaments while atthe same time substantially to reduce or eliminate entirely the garishsparkle.

Patented Sept. 9, 1969 "ice Therefore, it is an object of this inventionto provide a spinneret and a spinneret assembly adapted for thepractical production of man-made filaments providing increased cover-bya reduction in the amount of polymer employed to constitute a filamentthrough the presence of a multitude of holes and lobes and exhibitingreduced prismatic luster.

A further object is to provide such man-made filaments as justdescribed.

Other objects may become apparent.

SUMMARY OF THE INVENTION A melt-spinning spinneret is made by cutting ina spinneret blank at least one hole of two different diameters. The holeextends from the melt face to the extrusion face with the largerdiameter-hole portion opening at the melt face and the smaller diameterhole portion opening at the extrusion face. For each hole an elongatedinsert member of two like outside diameters are shaped and force-fittedinto the holes. The length of the insert is preferably greater than thethickness of the spinneret. A counterbore is cut in the larger end ofthe insert. A series of small passageways are cut between thecounterbore and the smaller end of the insert. The small passageways arearranged to produce a complex hollow textile filament by the coalescenceof a cluster of small streams of polymer normally issuing therefrom. Thespinneret is placed in a conventional spinneret block of a melt-spinningapparatus. An annular member having exhaust ports for directing a streamof coolant onto the coalescing filaments is positioned around theextending ends of the inserts to provide controlled cooling of thestreams of molten polymer forced through the spinneret orifices. Theresulting filament is multilobal and has a central axially extendinghole and a smaller axially extending hole in each of the lobes of thefilament. The total cross-sectional area of the filament is 2050% void;and the cross-sectional area of each of the voids in the lobes beingabout 10-75% of the cross-sectional area of the central void.

DESCRIPTION OF THE DRAWING The invention can best be understood byreference to the following description taken in conjunction with theaccompanying drawing in which:

FIGURE 1 is a cross-sectional view of the spinneret assembly;

FIGURE 2 is a bottom of the spinneret plate and the distribution systemof the coolant for solidifying the filaments;

FIGURE 3 is an enlarged cross-sectional view of the annular ring in thecoolant distribution system;

FIGURE 4 is a bottom view of part of a spinneret plate showing onearrangement of an orificial group for producing a filament of multiplelobes and multiple holes;

FIGURE 5 is a view of a second embodiment of a group of orifices;

FIGURE 6 is a cross-sectional view of a melt-spun filament produced inaccordance with the present invention.

With reference to FIGURE 1 there is shown a spinneret assembly adaptedfor melt spinning multilobal filaments having a plurality of continuousaxially extending holes. The assembly comprises a spinneret block 1which is a part of conventional melt spinning apparatus. A spinneretplate 2 is carried in the block in sealed relation ship. A plurality ofholes 3 extend from the melt face 4 of the spinneret to the extrusionface 5 thereof. The holes are provided with an upper hole portion 6 oflarger diameter and a lower hole portion 7 of smaller diameter. In eachof the holes 3 is an insert member 8. This elongated insert member hasportions of different outside diameters corresponding to upper and lowerhole port1ons.

A counterbore extends from the larger end of the insert; and a pluralityof small complex extrusion orifices 11 extend from the smaller end ofthe insert to establish communication with the correspondingcounterbore. The smaller end of the insert extends slightly below theplane of the extrusion face of the spinneret face.

An annular ring 12 is positioned in encircling relation with each of theportions of the insert member that extend below the plane of thespinneret plate. A source of coolant 13 is provided; and the coolant inthe form of air, steam, inert gas, Water and the like is suppliedthrough a manifold distributing system 14 to the individual rings. Ascan be seen in FIGURE 3 the rings have an exhaust port 15 in the form ofan inwardly opening annular slit from which the coolant exits and isdirected onto the filaments to solidify the filaments as desired. Wherea filament corresponding more closely to the shape assumed atcoalescence is wanted, one may induce a quicker quenching of the meltspun filament by providing an increased rate of heat exchange.

The exit angle a of the coolant can be any suitable angle of 0 to 80.The plane of the bottom of the insert member will normally be below thelowest point of the ring. In this manner the bottom of the insert memberwill be easily accessible for removal of any undesirable polymerdeposits that may form on the edges of the orifices during spinning.However, if the exit angle requires the ring to be below the face of thecapillaries in operation, the ring and distribution system should bedesigned so as to be recessed against the face of the spinneret duringcleaning of the insert member.

In FIGURE 2 it is seen that the distribution system 14 includes aconduit 16 connecting the source of coolant supply 13 to distributor 17from which the coolant is apportioned to the rings 12 via smallerconduits 18.

FIGURE 4 shows one preferred orificial grouping for making themulti-hole, multi-lobe filament of the present invention. In thisarrangement three elongated extrusion orifices 20 are cut in insert 8and arranged in a segmented pattern. Six elongated orifices 21 arrangedin pairs corresponding in number to the number of lobes in the filamentsbranch outwardly from the annularly arranged orifices. The two branchingorifices of each pair are bent to provide closely-spaced relation at theends thereof. All the orifices of the group are spaced and arranged toprovide coalescence of the polymer streams normally issuing therefrominto filaments having multiple lobes and axially extending multipleholes.

FIGURE 5 shows another preferrd orificial grouping for making the typeof filaments described herein. In this case six elongated extrusionorifices 22 extend through the bottom of insert 8 and arecircumferentially arranged in a segmented pattern. One orifice 23branches outwardly from each of the annular arranged orifices 22. Thebranching orifices are arranged by pairs, each member of which has endsbent together to provide closely spaced relation. Again, all theorifices of the group are spaced and arranged to provide coalescence ofthe polymer streams into multi-hole, multi-lobe filaments.

FIGURE 6 shows a cross-section of a typical filament 24 obtained byusing either of the two disclosed clusters of orificial groupings. Thefilament, if completely solid, would present scintillations of reflectedlight normally characterizing lobular filaments of this type. However,the filaments herein have a multitude of axially extending voids andexhibit considerably reduced scintillations. In many cases thescintillations may not be manifest at all. In any event, thescintillations are of a much finer scale and of a reduced intensity.Each lobe of a filament has an axially extending hole 25 which issmaller compared to the one central axially extending hole 26. The totalcross-sectional area of the filament is 20-50% void;

that is, the percentage of the total area defined by the periphery ofthe filament and made up of void area is 2050. Below 20% the amount ofvoid area is not sufficient to provide optimum covering power in thefilament; and one does not obtain a reduction in scintillation andpolymer usage to be practical. Above 50% collapsing of the filament mayoccur unless expensive care is exercised during filament formation toprevent this. The holes in the lobes are smaller than the central holein the filaments. It is preferred that the cross-sectional area of eachof the voids in the lobes be about 10-75% of the cross-sectional area ofthe central void in order to obtain optimum balance of greater cover andresistance to collapsing.

The spinneret can be used to produce filaments from any suitablesubstance that can be melt spun. Specific polymeric materials capable ofbeing melt-spun include: nylon-66 (polyhexamethyleneadipamide), nylon-6(polycaprolactam), nylon-4, nylon-610, nylon-ll, and theirfilament-forming copolymers thereof, e.g., nylon-6/66, 6/610/66, etc.;polyester derived from terephthalic acid or derivatives thereof andethylene glycol; polyethylene and polypropylene; and other fiber-formingsubstances. By providing a proper molten polymer distribution system thespinnerets herein can be used to produce .multicomponent crimpablefilaments having a side-by-side arrangement of dissimilar polymers.

The actual dimensions of the openings comprising an orificial groupdepend, of course, upon the characteristics of the polymer, the filamentsize or denier, the spinning speed, the temperature and nature of thecoolant, and other factors in the particular melt-spinning processes.However, a spinneret for melt-spinning nylon-66 into filaments describedabove was made from a stainless steel spinneret blank of the followingdimensions. The blank had a diameter of 2.030 inches and a thickness of0.190 inch. Six orificial groupings were arranged in the spinneret andequally circumferentially spaced. The centers of each group were on aradial line 0.50 inch from the center of the spinneret blank. Six flatbottom round counterbores of 0.125 inch were drilled in the spinneret toa point of 0.020 inch from the face of the spinneret. From the bottom ofthe counterbore to the face of the spinneret a cluster of orifices asshown in FIGURE 5 was machined using an electroerosive technique. Thecircumfcrentially arranged slots were 0.003 inch thick and 0.027 inchlong. Each was spaced 0.002 inch apart. The branch ing slots were 0.003inch thick, 0.031 inch long, and were separated at their point ofnearest approach of 0.003 inch The spinneret was placed in aconventional melt-spinning equipment. The coolant supply system wasinstalled as shown in FIGURE 2. Nitrogen gas at 68 C. was supplied tothe six spinning points via the system at a rate of 5 cubic feet perminute. Nylon-66 polymer of a relative viscosity of 42 was melted andforced through the spinneret holes. The yarn was given an orientationstretch and woven into fabric. It was noted that the yarn had across-section as that in FIGURE 6. The yarn provided increased cover inthe fabric, and it was noted that the yarn did not have the tiny sparklenormally associated with trilobal yarn.

It is apparent from the foregoing description that this inventionrepresents a substantial advance in the art of spinneret manufacture andtextile yarn made therefrom. The spinneret can be made with facility.Yarn made therefrom has a considerably large void area, This can beaccom lished at high spinning speed. The prismatic luster of the presentlobular yarn is of a much finer scale than that of similar lobular yarnnot having the internal void arrangement of the present invention.

It is apparent that many different embodiments of this invention can bemade without departing from the spirit and scope thereof; and,therefore, it is not intended to be limited except as indicated in theappended claim.

We claim:

1. A method of manufacturing a melt-spinning spinneret comprising:

(a) cutting in a spinneret a hole of two different diameters extendingfrom the melt face to the extrusion face thereof, the large diameterhole portion opening at the melt face and the smaller diameter holeportion opening at the melt face;

(b) for each hole forming an elongated insert member of two like outsidediameters for ositioning in tight sealing relationship in said hole, thelength of the insert being greater than the thickness of the spinneret;

(c) cutting a counterbore in the larger end of said insert;

(d) cutting a series of small passageways extending between thecounterbore and the smaller end of said insert, the small passagewaysbeing adapted to proface.

References Cited UNITED STATES PATENTS 3,114,966 12/1963 Fell 761073,174,183 3/1965 Siegel 76107 X 3,323,168 6/1967 Drunen et al 188 15BERNARD STICKNEY, Primary Examiner US. Cl. X.R. 188; 57-14()

